KR20010041377A - Lubricating composition - Google Patents

Abstract

The present invention relates to a lubricating composition comprising a hydrocarbon lubricant base oil in combination with (a) phenyl-naphthylamine, (b) thiophosphate, and (c) diphenyl amine, preferably (d) asperic acid ester. will be. The invention also relates to the use of a lubricating composition for lubricating a combination of a gas turbine and a steam turbine.

Description

Lubrication composition {LUBRICATING COMPOSITION}

The present invention relates to a lubricating composition, and more particularly to a lubricating composition for lubricating a combination of a steam turbine and a gas turbine.

Using a combination of gas and steam turbines to generate power has the advantage of being more efficient than generating power using either type of turbine. In the following the binder will also be referred to as the "bond cycle". The difficulty in lubricating the joining cycle lies in the wide variety of components that must be lubricated: bearings (both journal and thrust), gears, hydraulic control systems, flexible couplings and oil shaft seals. Although each component can be lubricated by itself, it is advantageous to have a single, common lubrication system that includes a single, common lubricant for all components.

Lubrication compositions used in common systems will have to have better requirements formulations in order to satisfactorily lubricate each component. While the requirements include more severe temperature and oxidative safety requirements and tighter foaming levels for the gas turbine section, the steam turbine section requires good water shedding properties and excellent corrosion resistance. High temperature oxidative stability means that the lubricating composition tends to form sludge at high temperatures and shows a low increase in viscosity and total acid value. Preferred properties show a viscosity increase of at most 20% and a total acid value of at least 3.0 mg KOH / g, and the oxidative stability carried out according to the high temperature deformations described in the General Electric specifications GEK 32568 C and GEK 101941. The sludge content after application to test DIN 51394 is less than 300 mg / 100 ml, preferably less than 250 ml / g, more preferably less than 200 ml / g and most preferably less than 150 mg / g. In setting the amount of sludge produced, the sludge should be carefully separated from all the equipment used for the test. The sludge is separated from the oil by filtration.

In particular, it has been found that the tendency of the lubricating composition to form sludge is important in the suitability of the combined cycle apparatus for lubricating the composition to lubricate.

The lubricating composition used in the bonding cycle must further have a specific viscosity index, pour point, filterability and antiwear performance, while at the same time the composition must provide adequate lubrication over the years.

In order to obtain this combination of complex lubricant properties, the lubricant must be suitable for use in the bonding cycle.

EP-A-696 636 discloses (A) lubricating base oil, (B) alkyl diphenylamine and / or phenyl-α-naphthylamine and (C) oxymolybdenum sulfide dithiocarbamate and / or oxymolybdenum sulfonate. It is taught to use a combination of feed organophosphorodithioates. One kind of alkyldiphenylamine may be used alone, or two or more kinds of alkyldiphenylamine may be used together. One kind of phenyl-α-naphthylamine may be used alone, or two or more kinds of phenyl-α-naphthylamine may be used together. In addition, one or more kinds of alkyldiphenylamine and one or more kinds of phenyl-α-naphthylamine may be used together. In the examples, alone alkyldiphenylamine or sole phenyl-α-naphthylamine is used. Oxymolybdenum sulfide organophosphorodithioate is present in only one embodiment according to the teachings. EP-A-696 636 does not disclose or teach the use of certain combinations of alkyl diphenylamines and phenyl-α-naphthylamines and thiophosphates.

It is also known to use blends of amine antioxidants optionally in combination with thiophosphates in ester base oils used in gas turbine engines for aviation purposes. Such formulations are described in GB-B-990,097, GB-A-2272000 and GB-B-1,293,245. This document does not disclose or teach the use of a combination of diphenylamine, thiophosphate and phenyl-α-naphthylamine in hydrocarbon lubricant base oils.

It has been found that the lubricating composition now has the requirements for use in the bonding cycle. The lubricating composition also exhibits a low tendency to form sludge, especially at high temperatures.

The lubricating composition according to the invention comprises a hydrocarbon lubricant base oil in combination with (a) phenyl-naphthylamine, (b) thiophosphate and (c) diphenyl amine.

According to the invention the lubricating composition may comprise a single compound or a mixture of compounds for each of components (a), (b), (c) and (d). The latter are the compounds according to formula I which will be discussed below.

Phenyl-naphthylamine used in the present invention may be substituted or unsubstituted, or a mixture of both. Phenyl-naphthylamine can be used as such or in the form of a salt. Preferred substituted phenyl-naphthylamine is mono-alkylated phenyl-alpha-naphthylamine. More preferred phenyl-alpha-naphthylamine is monooctylated phenyl alpha-naphthylamine.

Phenyl-naphthylamine is preferably phenyl-alpha-naphthylamine.

Phenyl-naphthylamine is preferably unsubstituted phenyl-alpha-naphthylamine. Industrially available phenyl-naphthylamine can be used in the present invention.

The lubricating composition according to the invention also comprises diphenylamine. Diphenylamine may be substituted or unsubstituted. Preference is given to using hydrocarbyl substituted diphenylamines, more preferably alkyl substituted diphenyl amines. Preferred diphenyl amines are 4,4'-dialkyl diphenylamines. The alkyl group preferably contains 2 to 15 carbon atoms, more preferably 5 to 12 carbon atoms. Preferred diphenyl amine is dioctyl diphenylamine.

Thiophosphate compounds may be thiophosphoric acid, substituted thiophosphoric acid, salts of thiophosphoric acid, and / or salts of substituted thiophosphoric acid. Preferably, the thiophosphate is substituted by one or more hydrocarbyl groups in which the hydrocarbyl group may comprise acid, hydroxy and / or ester groups. The hydrocarbyl group moiety is preferably alkyl containing up to 12 carbon atoms. Hydrocarbyl substituted thiophosphates are preferably mixtures of thiophosphates comprising two or three hydrocarbyl groups or comprising two to three hydrocarbyl groups.

Thiophosphates can include any number of sulfur atoms bonded directly to the phosphorus atom. Preferably, the thiophosphate is monothiophosphate and / or dithiophosphate.

Thiophosphate acid or one of its salts may be used in the present invention. Preferably, salts of thiophosphates are used. More preferably an amine salt of thiophosphate is used. More preferred thiophosphates and their preparation are described in EP-A-375324. A suitable thiophosphate that can be used industrially is LZ 5125 from Lubrizol Corporation.

The hydrocarbon lubricant base oil present in the lubricating composition of the present invention may be any hydrocarbon oil suitable for use in lubricants. Other suitable base fluids may have different lubrication viscosities. Hydrocarbon base oils consist mainly of compounds containing only hydrogen and carbon. There may be a limited amount of contaminants such as sulfur, including compounds. Preferably, at least 80% by weight, more preferably at least 90% by weight of the base oil consists of a compound consisting solely of hydrogen and carbon. The base oil may be a natural or synthetic lubricant, or a mixture thereof. Natural oils are solvent- or acid-treated paraffinic, naphthenic, or mixed paraffinic, which may be further refined by mineral oils such as liquid petroleum or hydrocracking and hydrofinishing processes and / or dewaxing. Light lubricating oil in the form of / naphthenic. Synthetic lubricants include hydrocarbon oils such as polymerized or copolymerized olefins. Preferably, the base oil is a mineral oil comprising less than 10% by weight, preferably less than 5% by weight and most preferably less than 3.0% by weight of aromatic compounds as measured according to DIN 51378. It is even more preferred that the base oil comprises less than 1.0% by weight, preferably less than 0.1% by weight, more preferably less than 0.05% by weight of sulfur, calculated from elemental sulfur and measured by ASTMD 4045. The mineral oil can be obtained by strict hydroprocessing. Preferably the lubricant base oil has a kinematic viscosity at 40 ° C. in the range of 5 to 220 cSt, more preferably 10 to 200 cSt, most preferably 20 to 100 cSt.

Preferably, the composition according to the invention does not comprise sulfided fatty acids. The amount of sulfided fatty acids is preferably less than 0.5% by weight, more preferably less than 0.1% by weight and most preferably less than 0.02% by weight, based on the total amount of the lubricating composition.

Optionally, the lubricating composition according to the invention comprises additional component (d) which is a compound according to formula (I)

[Wherein R ₁ and R ₂ are each hydrogen or alkyl or hydroxyalkyl having 1 to 30 carbon atoms; R ₃ , R ₄ and R ₅ are each hydrogen or alkyl having 1 to 4 carbon atoms, X is CH or N and R ₆ and R ₇ are each hydrogen, alkyl or alkenyl having 1 to 30 carbon atoms, or Or an acyl group derived from substituted or unsubstituted carboxylic acid having up to 30 carbon atoms. Preferably, R ₁ and R ₂ are each alkyl having 3 to 6 carbon atoms, R ₃ , R ₄ and R ₅ are each hydrogen, X is N and R ₆ and R ₇ are each 15 to 20 carbon atoms Or an acyl radical derived from saturated or unsaturated dicarboxylic acid having 4 to 10 carbon atoms, and at least one of R ₆ and R ₇ is an acyl group. Especially preferred are aspartic acid and N- (3-carboxy-1-oxo-2-propenyl) -octadecyl-bis (2-methylpropyl) ester. The aspartic acid esters are industrially available.

The lubricating composition according to the invention preferably does not contain a substantial amount of phenolic antioxidant. Use of phenolic antioxidants, more particularly alkylated phenols such as 2,6-di-tert.butyl-phenol and 4,4 '(methylenebis (2,6-di-tert.butyl-phenol)) It was found to increase the sludge formed at high temperatures. It is also known that low molecular weight phenolic antioxidants tend to evaporate. This results in malfunction of the residue of the lubricating composition. The amount of phenolic antioxidant present is preferably less than 1% by weight, more preferably less than 0.5% by weight and most preferably less than 0.1% by weight, based on the total amount of the composition.

The lubricating composition may also include conventional additives. The composition also preferably includes a metal passivator, a rust inhibitor, a foam inhibitor and / or an emulsifying breaker. Component (d) is a preferred rust inhibitor.

The amount of additive present in the lubricating composition depends on the specific compound used.

Typically, the lubricating composition preferably comprises between 0.1 and 5.0 wt%, preferably greater than 0.2 wt% and preferably less than 2.0 wt%, phenyl-naphthylamine, 0.01 to 1.0 wt%, based on the total amount of the composition, Preferably thiophosphate between more than 0.02% and preferably less than 0.5% by weight, and diphenyl amine between 0.1 and 5.0% by weight, preferably more than 0.2% by weight and preferably less than 2.0% by weight, 0 to 1.5% by weight, preferably 0 to 1.0% by weight of the compound according to formula (I); And at least 95% by weight of base oil, preferably mineral oil.

The invention also relates to the use of a lubricating composition according to the invention for lubricating a combination of a gas turbine and a steam turbine, more preferably the combination using a pressurized-steam generator. The invention also relates to lubricating a combination of a gas turbine and a steam turbine using a pressurized-steam generator.

Lubrication compositions according to the present invention may be prepared by the addition of phenylnaphthylamine, thiophosphate, diphenylamine, hydrocarbon base oils and optionally compounds according to formula (I).

Experiment

The formulations were subjected to a test for high temperature oxidative stability, known as the oxidation test DIN 51394, carried out according to the high temperature variants described in the general electrical specifications GEK 32568 C and GEK 101941. In this test, the oil is held at 175 ° C. for 72 hours in the presence of five metal catalysts (copper, steel, aluminum, magnesium, silver) while air bubbles through the oil at a ratio of 3 L / hour. At the end of the test, the oil is analyzed for its viscosity increase, and the acid value and the total amount of sludge produced. The sludge must be carefully separated from the device, in particular from a sufficiently high place on the side of the cylinder. The sludge is filtered off using 5 micron filter paper, available from Millipore, the separated sludge is washed with n-hexane and then dried and weighed.

The formulation includes the following additives.

Amine Antioxidant I: Phenyl-alpha-naphthylamine (unsubstituted)

Amine Antioxidant II: Dioctyl Diphenyl Amine

Rust inhibitors: aspartic acid, N- (3-carboxy-1-oxo-2-propenyl) -N-octadecyl, bis (2-methylpropyl) ester.

Abrasion inhibitors: Amine salts of dialkylthiophosphates, LZ 5125, industrially usable from lubrizol.

The additives comprise less than 3% by weight of aromatic compounds (measured by DIN 51378) and less than 0.05% by weight of sulfur compounds (measured by ASTM D 4045) as calculated by elemental sulfur and include conventional metal passivating agents, foams It is added to the base oil further comprises an inhibitor and an emulsifying breaker. For compositions 1 and 2, base fluid A is used. For compositions 3 to 5, base fluid B is used. The fluid is different in conventional metal passivating agents present.

The amount is% by weight relative to the total amount of the formulation, including mineral oil.

Composition

One 2 (comparative) 3 4 (comparative) 5 (comparative) Base fluid A A B B B Amine Antioxidant Ⅰ 0.5 0.5 0.5 1.0 - Amine Antioxidant II 0.5 0.5 0.5 - 1.0 Antiwear 0.1 - 0.1 0.1 0.1 Rust inhibitor 0.1 0.1 0.1 0.1 0.1 Sludge formation (mg / 100 ml) 190 360 144 234 352

Claims (7)

Lubrication composition containing a hydrocarbon lubricant base oil in combination with: (a) phenyl-naphthylamine, (b) thiophosphate, and (c) diphenyl amine. A lubricating composition according to claim 1, further comprising (d) a compound according to formula (I): [Formula I] [In the meal, R ₁ and R ₂ are each hydrogen or alkyl or hydroxyalkyl having 1 to 30 carbon atoms; R ₃ , R ₄ and R ₅ are each hydrogen or alkyl or hydroxyalkyl having 1 to 4 carbon atoms; X is CH or N; R ₆ and R ₇ are each hydrogen or alkyl or alkenyl having 1 to 30 carbon atoms, or an acyl group derived from saturated or unsaturated carboxylic acid having 30 or less carbon atoms. The lubricating composition according to claim 1 or 2, containing less than 0.02% by weight of sulfurized fatty acids. The lubricating composition according to any one of claims 1 to 3, which contains as a base oil less than 10% by weight of aromatic compounds and mineral oil containing less than 1.0% by weight of sulfur calculated from elemental sulfur. The lubricating composition of claim 1, wherein the lubricating composition further contains a metal passivator, a rust inhibitor, a foam inhibitor, and / or an emulsifying breaker. The method according to claim 1, wherein, based on the total amount of the composition, 0.1 to 5.0 wt% phenyl-naphthylamine, 0.01 to 1.0 wt% thiophosphate, 0.1 to 5.0 wt% diphenyl A lubricating composition comprising amine, 0 to 1.5% by weight of a compound according to formula (I), and at least 95% by weight of mineral oil. Use of a lubricating composition according to claim 1 for lubricating a combination of a gas turbine and a steam turbine.